Separate, but they do work together, as in Taipei there is someone from Thai immigration who conducts interviews and decides if the DTV is issued. They had the record of all my visits to hand inc transits and it is included in my file. Upon arrival i was asked about the work i do online. From a basic security view, it imakes sense info is shared.
The approval time is reset once they receive your docs, you sent the docs Dec 2nd, Dec 3 the approval process starts again. Berlin takes 15 business days to approve the application. Dec 5, 10 national Thai holidays.
Multiple accounts are no prob. Having one speeds up the approval process a bit. Vietnam, Laos, Indonesia are nearby, great options to apply. Takes around 10 busines days can be quicker though.